In mobile communication devices, such as mobile phones for example, it is becoming more and more imperative for manufacturers to provide low power solutions. Low power consumption is desirable because it helps to extend the useful battery life of mobile communication devices without a user having to recharge the battery of the device, among other things.
As shown in FIG. 1, a conventional mobile communication device 100 can include a signal generation unit 102 that provides a signal-of-interest, s(t), wherein the signal-of-interest has a low output power that needs to be amplified before transmission. In some examples, the signal generation unit 102 includes a baseband processor, and the signal-of-interest, s(t), represents data to be transmitted by the mobile communication device. For example, the signal-of-interest can represent a person's voice, such as detected by a microphone of the mobile communication device 100 during a phone conversation, and/or other data (e.g., text message, Internet data, music data, image file).
The mobile communication device 100 also includes a radio-frequency (RF) power amplifier 104, which is powered by a DC power supply, such as a DC/DC converter (not shown). The RF power amplifier converts the low-power signal-of-interest into an amplified signal of significant power, typically to drive an antenna 106 of the mobile communication device. Because the power amplifier 104 provides a large gain, the power amplifier 104 outputs a large output signal power based on a small amount of RF input power. The division between the low-power signal generation unit 102 and the power amplifier 104 helps provide a relatively good balance between low power consumption (e.g., facilitated by carrying out signal processing in the signal generation unit 102) and accurate signal transmission (e.g., facilitated by high output power from the power amplifier 104).
Although this basic architecture in FIG. 1 is well-known, the applicants have appreciated that the power amplifier 104 can make a significant contribution to the overall power consumption of the mobile communication device 100. Consequently, in an effort to limit overall power consumption of mobile communication transmitters while still retaining sufficient gain, sufficient modulation accuracy, and sufficient leakage power requirements in adjacent channels; the applicants have devised DC power control techniques for power amplifiers as described herein.